Researchers from the National Institute of Allergy and Infectious Diseases (NIAID) at the National Institutes of Health (NIH) have recently identified a cellular protein that helps guide immune cells to the gut as a target of HIV.
NIAID scientists identified the cell adhesion molecule known as integrin alpha 4 beta 7 as another potentially important HIV receptor. HIV has been found to bind to several other immune cell receptors – the primary receptor being the CD4 molecule. CCR5 and CSCR4 serve as co-receptors used by HIV to enter target cells.
During the early stages of HIV infection, the virus invades and replicates in the immune cells of the gut - the gut-associated lymphoid tissue (GALT). The gut is then rapidly depleted of CD$+ T cells, thus triggering the process that leads to AIDS. The natural function of alpha 4 beta 7 is to direct T cells to the GALT. NIAID researchers fond that the gp120 protein (part of the HIV envelope) binds to integrin alpha 4 beta 7 on CD4+ T cells, which facilitates the formation of stable junctions between neighboring cells. This ability allows HIV to readily gain access to uninfected cells!
Read more on what NIAID scientists are up to at http://www.nih.gov/news/health/feb2008/niaid-10.htm.